Although the application of Laser Scattering Spectroscopy to detect ciliary activity in vitro is now well established, the use of fiber optics, which is required for laser scattering to detect ciliary motions in situ, induces a great deal of optical noise and deteriorates the performance of this method for applications in vivo. To avoid this inconvenience we have designed a new triple-fiber optic catheter and the use of differential spectral analysis for processing the scattering data. We have experimentally demonstrated the feasibility of this idea. Our engineering efforts during last year were concentrated in the design and development of a low frequency Fast Fourier Transform Digital Spectrum Analyzer which was fabricated and is undergoing final tests of evaluation. The construction of a triple fiber catheter is currently being undertaken. The application of laser scattering to study the regulation of ciliary activity and the role of this cation on stimulus-motility coupling of hormonal stimulation of ciliary activity. During last year, we completed the study of the effect of Ca2 ions on ciliary activity and the role of this cation on stimulus-motility coupling of hormonal stimulation of ciliary activity. We also completed our studies stimulating effect of beta-acheneigic influence on respiratory cilia. We have advanced our studies on the objective quantitation of the effect of serum of Cystic Fibrosis patients on ciliary activity: we have observed that our assay in cultured ciliated cells of the rabbit trachea is also sensitive to serum of CF carriers, a finding that may have most important implications.